When your head starts to pound and you reach for the bottle of Advil, it's easy to take what the medication does for granted.
But how does that swallowed pain reliever actually work so that your head can clear up a half hour later?
Once a pill or liquid solution gets swallowed, it travels through the body and is absorbed into the bloodstream. At that point, the blood carries the medicine to different parts of the body, looking for the pain.
Note that the medicine isn't exactly going to a specific spot: The painkiller will go ahead and get to work, regardless of whether an area has pain or not. That's why if you have a headache you're trying to treat, you might start to feel less pain in your legs that are sore after a tough work-out.
But how they go about doing so differs from one type of pain reliever to another.
NSAIDs
Ibuprofen (Advil), naproxen (Aleve), and aspirin, are all part of a class of medications called non-steroidal anti-inflammatory drugs. They treat aches by reducing inflammation (which can be anything from heat, fever, swelling, pain or losing movement). Say you've strained your back muscles while moving into a new apartment: the body's white blood cells goes into that spot to repair the muscle, causing swelling and heat that can lead to pain. (This is one reason some pain can be good: It's your body saying, I'm hurt — go easy on me.)
At a chemical level, as a 2012 TED video puts it, aspirin and ibuprofen (along with naproxen) work by latching onto to an enzyme called cyclooxygenase, blocking it out. This keeps the body from making a molecule called prostaglandin, which generates the inflammation that often leads to pain. With that molecule blocked, the pain begins to subside.
Tylenol
Although Tylenol has been marketed since the 1950s, we still don't have much of an idea about how it works. As one researcher put it to Carmen Drahl, for a story in C&E News, "It’s not an opioid, and it's not an NSAID ... The question is — what is it?"
Though there are a number of theories — for example, it might have a lot to do with inhibiting the same enzyme the NSAIDs do — all we know is that it's used to treat pain and fever. Unlike the NSAIDs, it doesn't treat inflammation.
Also of note: Tylenol, when too much is taken, can lead to serious liver damage, according to the FDA.
What's the best pain reliever to use?
The chart below summarizes what studies have shown to be the best pain relievers for a specific symptoms (though many of the drugs can be used for a number of other symptoms).
As always, if you're experiencing unusual pain and wondering how to treat it, talk to your doctor.
